The Living Planet Index, which measures trends in thousands of vertebrate species populations, shows a decline of 52% between 1970 and 2010, according to the latest edition of WWF's Living Planet Report.

In other words, the number of mammals, birds, reptiles, amphibians and fish across the globe is, on average, about half the size it was 40 years ago.

Biodiversity is declining in both temperate and tropical regions, but the decline is greater in the tropics, the World Wide Fund for Nature report indicates. The tropical LPI shows a 56% reduction in 3,811 populations of 1,638 species from 1970 to 2010. Latin America shows the most dramatic decline – a fall of 83%.

Habitat loss and degradation, and exploitation through hunting and fishing, are the primary causes of decline. Climate change is the next most common primary threat, and is likely to put more pressure on populations in the future.

Terrestrial species declined by 39 per cent between 1970 and 2010, a trend that shows no sign of slowing down.

The LPI for freshwater species shows an average decline of 76 per cent. The main threats to freshwater species are habitat loss and fragmentation, pollution and invasive species.

Marine species declined 39% between 1970 and 2010.

WWF's Living Planet report is published every two years. The last one showed a 28% decrease in vertebrate species populations, Dnevnik.bg notes.